On Sat, Jan 25, 2003 at 08:41:56PM -0600, Dan Minette wrote:
> industry. The g force for something dropped from a meter onto a hard
> surface is typically around 1000 g's. The shock pulse is about 0.005
> s wide.
Integrate[a*t, {t,0,T}] == Sqrt[ 2 g h]
If h is 1 meter and g is 9.8 m/s^2, then the right side is about 4.4m/s.
However, if the average acceleration is 1000g for 0.005s, then the left
side is 49m/s. It seems the impulse you quote is a factor of 10 higher
than the speed corresponding to 1 meter.
It seems to me either there is a lot of "bouncing" and deformation my
analysis neglects, or the impulse you quote is too high (maybe the shock
pulse is 0.5ms wide, not 5ms?). Comments?
Out of curiousity, what shape do you find for the a vs. t curve? Does
it increase from 0 to a high value in, say microseconds, and then stay
there for about 5ms, and decrease rapidly? Or is it more triangular
shaped? It's not asymmetrical is it?
> There are specifications I've written for detectors (comprising of a
> photomultiplier tube and a NaI crystal) to survive these shocks, as
> well as 6 hours of 20 g rms random vibration.
My first impulse (pun intended) would be to pot it in some high
temperature silicone RTV and see how much that spreads out the force
over time. Maybe another layer of some other high temperature foam with
different compressability on top of that. How did you solve it? (Or is
that a trade secret :-)
--
"Erik Reuter" <[EMAIL PROTECTED]> http://www.erikreuter.net/
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